Electric Bicycle Motor System

ABSTRACT

An electric motor bicycle system with an electric motor driven gear adapted to drive a wheel gear coupled to a bicycle hub. The motor driven gear is coupled to the wheel gear with a chain. The chain may be tensioned with one or more tensioners, which allow for a tighter system geometry. The motor may be supported with a bracket adapted to mount to industry standard disc brake mounting interfaces. In some aspects, the motor driven gear is coupled to the disc mounting interface of a wheel hub. In some aspects, the electric motor bicycle system may also have a disc brake system integrated therein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/541,130 to Saiki, filed Aug. 14, 2019, which claims priority to U.S.Provisional Patent Application No. 62/718,921 to Saiki, filed Aug. 14,2019, which is hereby incorporated by reference in its entirety, andwhich also claims priority to U.S. Provisional Patent Application No.62/785,263 to Saiki, filed Dec. 27, 2019, which is hereby incorporatedby reference in its entirety.

BACKGROUND Field of the Invention

The present invention relates to electric transport, and morespecifically to an electrically powered bicycle motor system.

Description of Related Art

Motivated by the environmental, public health, ecological, andcarbon-footprint issues associated with gasoline-powered automobiles,researchers, governments, and society as a whole have been engaged in asearch for viable alternatives. Electric bicycles (e-bikes), which arepropelled by a combination of pedaling and battery-powered electricmotors, are a promising alternative to automobile transportation. Theirprimary advantages include lower purchase and operating costs comparedto cars, ability to travel longer distances and with less physicaleffort compared to traditional bicycles, and zero emissions duringoperation.

Regenerative braking is a unique technique that is used in EVs tocapture energy that the vehicle has due to its motion or, in otherwords, its kinetic energy that would have been wasted when the vehicledecelerates while braking. By taking a measure of the initial and finalvehicle velocity, the amount of kinetic energy which is lost to brakingcan be calculated.

Urban drive cycles have a considerable amount of acceleration anddecelerating periods due to traffic control systems in place aroundtowns and cities, and therefore, when decelerating, significant energyis lost. However, with regenerative braking, this energy can becaptured, and ‘waste’ energy can be harnessed and utilized for vehiclepropulsion. Similarly, off road cycles also have a considerable need foracceleration and deceleration due to climbing and descending hills.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an electric bicycle motor systemaccording to some embodiments of the present invention.

FIG. 2A is a left side view of a bicycle with an electric bicycle motorsystem mounted thereon according to some embodiments of the presentinvention.

FIG. 2B is a top view of a bicycle with an electric bicycle motor systemmounted thereon according to some embodiments of the present invention.

FIG. 3 is a right side view of an electric bicycle motor systemaccording to some embodiments of the present invention.

FIG. 4 is a left side view of an electric bicycle motor system accordingto some embodiments of the present invention.

FIG. 5 is a side cross-sectional view of an electric bicycle motorsystem according to some embodiments of the present invention.

FIG. 6A is an isometric view of bicycle with an electric bicycle motorsystem mounted thereon according to some embodiments of the presentinvention.

FIG. 6B is an isometric view of bicycle with an electric bicycle motorsystem mounted thereon according to some embodiments of the presentinvention.

FIG. 7 is an isometric view of a mounting bracket for an electricbicycle motor according to some embodiments of the present invention.

FIG. 8A is an exploded isometric view of an electric bicycle motorsystem according to some embodiments of the present invention.

FIG. 8B is an interior view of a motor housing according to someembodiments of the present invention.

FIG. 9 is a left side view of a bicycle with an electric bicycle motorsystem mounted thereon according to some embodiments of the presentinvention.

FIG. 10 is an isometric view of an electric bicycle motor systemaccording to some embodiments of the present invention.

FIG. 11 is a side cross-sectional view of an electric bicycle motorsystem according to some embodiments of the present invention.

FIG. 12 is an isometric view of an electric bicycle motor system with adisc brake according to some embodiments of the present invention.

FIG. 13 is a cross-sectional view of an electric bicycle motor systemwith a disc brake according to some embodiments of the presentinvention.

FIG. 14 is an exploded isometric view of an electric bicycle motorsystem according to some embodiments of the present invention.

FIG. 15 is an isometric view of a mounting bracket for an electricbicycle motor according to some embodiments of the present invention.

FIG. 16 is an isometric view of a mounting bracket for an electricbicycle motor according to some embodiments of the present invention.

FIG. 17A illustrates a bracket according to some embodiments of thepresent invention.

FIG. 17B illustrates a mounting interface according to some embodimentsof the present invention.

FIG. 18 is a flow chart of the motor and battery system according tosome embodiments of the present invention.

SUMMARY OF THE INVENTION

An electric motor bicycle system with an electric motor driven gearadapted to drive a wheel gear coupled to a bicycle hub. The motor drivengear is coupled to the wheel gear with a chain. The chain may betensioned with one or more tensioners, which allow for a closely spacedsystem geometry. The motor may be supported with a bracket adapted tomount to industry standard disc brake mounting interfaces. In someaspects, the motor driven gear is coupled to the disc mounting interfaceof a wheel hub. In some aspects, the electric motor bicycle system mayalso have a disc brake system integrated therein. The electric motorbicycle system may include a regenerative braking system, which may be afully proportional regenerative braking system.

DETAILED DESCRIPTION

In some embodiments of the present invention, as seen in FIGS. 1, 3, 4,and 5 , an electric bicycle motor system 100 couples a motor unit 101 todrive gear 102 with a drive chain 103. The motor unit 101 is coupled toa mounting bracket 110, which is adapted to mount the motor unit 101 toa bicycle. In some aspects, the mounting bracket 110 is adapted to mountthe rear disc brake mounting interface 107 of the bicycle. In someaspects, the mounting bracket 110 is adapted to mount to an industrystandard brake mounting interface. With such a system, a non-electricbicycle may be converted into an electric bicycle. In some aspects, theelectric bicycle system is adapted to be mounted to a customizedmounting interface.

In an exemplary application, as seen in FIGS. 2A and 2B, an electricbicycle system 100 may be installed onto an existing bicycle designed toaccommodate a rear disc brake system. A rear wheel assembly on a bicyclemay include a rim 106 with a tire 105 mounted thereon. The rim 106 maybe coupled to a hub which includes a disc mounting interface 109. A reardisc brake mounting interface 107 may reside on the rear portion of theframe 104. Instead of installing the rear disc and the rear disc brakemechanism, the mounting interface 119 of a gear 102 may be mounted ontothe rear hub's disc interface 109. A bracket 110 adapted to support amotor unit 101 is mounted onto the disc mounting interface 109, and themotor unit 101 is coupled to the bracket 110. In this way, the electricbicycle system 100 is easily incorporated into an industry standardbicycle without any rework or additional mounting changes or bracketsrequired. The use of the electric bicycle system as a rear brake brakingsystem obviates the need for the rear disc brake, allowing for the useof disc and disc brake mechanism mounting interfaces for the drive gear102 and the motor unit 101 and motor bracket 110. In some aspects, thereis no other rear braking mechanism on the bicycle other than that of themotor unit used as a brake. In some aspects, the gear 102 is mountedonto a wheel hub mounting interface and the gear interface consists of asix hole pattern with holes of approximately 5 m diameter on a boltcircle with a 44 mm diameter.

The rotational axis 108 of the rear wheel 106, which is coaxial to therotational axis of the drive gear 102, is marked along a front to backaxis of the bicycle by a station 153, and indicated in FIG. 2A. In someaspects, the bicycle frame is constructed such that the rear wheel willmount into a fixed position in the frame, such that the frame will havea rear wheel mounting axis which will be coaxial to the rear wheelrotational axis when the bicycle is assembled. A longitudinal axis 156of the bicycle is used to represent positional stations of componentswith regard to a front to rear aspect. The rotational axis of the motorunit 101 is marked along the longitudinal axis of the bicycle by astation 152, which is forward along the longitudinal axis of the bicyclerelative to the station of the rotational axis of the rear wheel 153.The forward station of the motor unit center of mass relative to therotational axis of the wheel allows for mounting of the motor unitwithout cantilevering the motor rearward of the rear wheel axis. In someaspects, the forward most position 155 of the wheel rim 106 along thelongitudinal axis 156 represents the farthest forward location of themotor rotational axis 112. In some aspects, the motor rotational axisresides along the longitudinal position axis 156 at a station betweenthat of the station 153 of the rotational axis 108 and the station 155of the forward most position 155 of the wheel rim 106. In some aspects,not only is the rotational axis of the motor not further forward of thestation 155 of the wheel rim 106, it is also not radially outside thewheel rim at other stations.

The rear wheel of the bicycle may have a pedal drive side, which iswhere the drive gear is mounted to the crank assembly. Similarly, theside of the bicycle frame which is on the side which has the pedal driveside of the crank may be referred to as the pedal drive side of theframe. In some aspects, the bicycle frame may not be symmetric from sideto side, which may be due to the presence of a derailleur dropoutcoupled to the frame, for example.

As illustrated in FIG. 2B, the inboard edge of the pedal (not shown)which is coupled to the crank arm 151 resides at a distanceperpendicular to the crank axis which is equal to or farther outboard ofthe outside surface of the motor unit 101. FIG. 2B is a top view of theembodiment seen in left side view in FIG. 2A. As illustrated in FIG. 2A,the motor unit 101 may have its rotational axis, and its center of mass,forward of the rotational axis of the rear wheel. In addition, the motorunit 101 may extend no farther outboard than the plane of the rotationalpath of the inboard edge of the pedal coupled to the crank, which willallow the foot of the user to clear the motor unit 101 in practice. Insome aspects, the motor unit clears the outboard surface of the crankarm. In some aspects, the motor unit will not protrude outboard of theoutboard surface of the crank arm with either a wider “Boost” crank, orwith a regular “non-Boost” crankset. In some aspects, the outermostportion of the motor unit will not protrude further outboard than theoutside surface of the crank arm, and the innermost surface of the motorunit will be outboard of any potentially interfering portion of the tireand wheel assembly. In some aspects, the outboard surface of the motorunit away from the center plane of the bicycle will be approximately inline with or inboard of the furthermost outside surface of the pedalcrank arm. In some aspects, the innermost surface of the motor unit willbe outboard of outboard surface of the wheel rim. In some aspects, theinnermost surface of the motor unit will be outboard of outboard surfaceof the tire. The very thin nature of the motor unit allows forpositioning of the motor unit in a location on the bicycle notpreviously obtainable.

FIG. 3 illustrates a rear view of the electric bicycle system 100according to some embodiments of the present invention. The electricbicycle system 100 includes two tensioning mechanisms 114, 117 whichallow for a significant amount of chain wrap around the pinion 111, aswell as providing dynamic stability of the chain 103 both during powertransmission to the rear wheel and during braking of the rear wheel bythe motor under braking. The motor unit 101 may have a rotational axis112 coupled to an exterior rotor which is coupled to a pinion 111. Insome aspects, as further illustrated in FIG. 8 , the motor 101 has anexternal rotor 135 coupled to the inboard housing 134 of the motor 101and which spins around an inboard stator 136 which is coupled to aninner stator 136. A first tensioner 114 is coupled to a first mountingpivot interface 115 and utilizes a first spring loaded gear 113 toprovide tension onto the chain 103. A second tensioner 117 is coupled toa second mounting pivot interface 118 and utilizes a second springloaded gear 116 to provide tension onto the chain 103. The stationaryoutboard housing 137 of the motor unit 101 is coupled to a mountingbracket 110, which may be attached to the rear disc brake mountinginterface of a bicycle with fasteners 120, 121. A drive gear mountingportion 131 is adapted to provide mounting of the drive gear 102 to themounting interface 119 on the rear hub.

In some aspects, the center to center distance between the rotationalaxis of the drive gear and the rotational axis of the motor is in therange of 100 mm to 350 mm. This broadest range is roughly bounded by theminimum center to center distance between two gears and a maximum centerto center distance that is bounded by the bicycle rim radius. In someaspects, the center to center distance between the rotational axis ofthe drive gear and the rotational axis of the motor is in the range of125 mm to 290 mm. This intermediate range provides better minimum chainwrap and less chain length. In some aspects, the center to centerdistance between the rotational axis of the drive gear and therotational axis of the motor is in the range of 150 mm to 230 mm. Thisnarrower range provides good chain wrap and minimized chain length. Inan exemplary embodiment the center to center distance is approximately187 mm.

In this illustrative embodiment, the pinion has 13 teeth. The number ofpinion teeth can be varied to provide a desirable gear ratio between thepinion and drive gear. In some aspects, the number of drive pinion teethhas a range between 9 to 30 teeth. In this illustrative embodiment, thedrive gear has 133 teeth. The number of drive gear teeth can be variedto provide a desirable gear ratio between the pinion and drive gear. Insome aspects, the number of drive gear teeth has a range between 60 to200 teeth. In general, the drive gear has more teeth in order to providea gear ratio that allows for the pinion to rotate faster than the drivegear thus providing for a gear reduction.

In an exemplary embodiment, the chain has a pitch of ¼ of an inch. Thisis a standardized chain pitch. In other aspects, there are other smalleror larger standardized chain pitches that would be function correctly.Chain pitches in Imperial units, metric units, or non-standardizedpitches could also be utilized. The approximate diameter of the pinionand drive gear is determined by the number of teeth times the chainpitch plus some additional diameter for tooth shape.

In some embodiments of the present invention, as seen in FIG. 4 , themotor unit 101 is coupled to the bracket 110 with fasteners 122, 123.The outboard motor housing 137 may have a slot 124 adapted to allow forsome adjustment of the position of the motor unit 101 relative to thebracket 110. FIG. 5 illustrates in cross-section the motor unit 101. Inthis view, the vertical alignment of the teeth of the pinion 111, thechain 103, and the teeth of the drive gear 102 are shown.

FIGS. 6A and 6B illustrate varying embodiments of the mounting bracketryfor a motor unit 101. FIG. 6A illustrates a bracket 110 which is coupledto the motor unit and also coupled the bicycle frame, and may be coupledto a disc brake caliper mounting interface in some aspects. FIG. 6Billustrates a bracket portion 110 a which is part of the bicycle frame.

Although discussed in the context of a bicycle, in some aspects thepresent invention may be seen in something other than a bicycle, such asa tricycle with two front wheels and a single rear wheel.

FIG. 7 illustrates a mounting bracket 110 according to some embodimentsof the present invention. The mounting bracket 110 includes throughholes 125, 126 which may be sized to mate to an industry standard discbrake mounting interface. A slot 131 may accommodate a mating portion152 of the outboard motor housing 137 of the motor unit 101, asillustrated in FIG. 8B. The fasteners 122, 123 which attach the motorunit to the bracket 110 may couple to receiving holes 127, 128, whichmay be threaded through holes in some aspects. In some aspects, thebracket 110 may have an extension arm 129 with a coupling pad 130 at itslower end. In some aspects, the coupling pad may reside against thebicycle frame to provide an additional support point adapted to offsetmoment loads which may be put into the bracket. In some aspects, theradial load through the pinion may result in some loads which are not inthe plane defined by the axis of the two receiving holes 127, 128. Insome aspects, a spacer may be bonded or otherwise affixed to the bicycleframe to provide a contact fit of the coupling pad 130 of the bracket110 to the bicycle frame.

FIG. 8A illustrates an exploded view of an electric bicycle system 100according to some embodiments of the present invention. A drive gear 102is coupled to a drive gear mount 143 with fasteners 132. The drive gearmount 131 may be adapted to interface with an industry standard reardisc mount on a rear wheel hub. A stationary outer motor housing 137 iscoupled to the internal stator 136. The internal stator 136 may havewindings and winding bars. An outboard bearing 139 resides within anoutboard recess in the outer motor housing 137 and an inboard bearing138 resides within an inboard recess in the outer motor housing. Theoutboard bearing 139 and the inboard bearing 138 support a motor shaftwhich is integral to the rotating inner motor housing 134. A retainer142 is coupled to the shaft of the inner housing 134 and axiallyconstrains the inner housing and the outer housing relative to eachother. A removable cover 141 is coupled to the outer housing 137 withfasteners 140, and allows for access to the retainer 142 and the outerbearing 139. The motor pinion 111 is mounted directly onto an integralinterfacing shaft extending from the inner motor housing 134 and iscoupled to the housing with a fastening coupler 133. An exterior rotor135 is coupled to the inner housing 134. The outer housing 137 iscoupled to the bracket 110 with fasteners 122, 123 and resides within aslot 131 which allows for some fitting of the bracket to the motor unitalong the direction of the main axis of the slot 131. FIG. 8B furtherillustrates details of the outer housing 137 according to someembodiments of the present invasion. The outer housing 137 may includean axial support portion 151 with a bearing receiver portion 150 adaptedto support the outer race of the inner bearing 138. A sliding form 152is adapted to reside within the slot 131 in the bracket 110, or otherbrackets. Slots 153, 154 in the outer housing 137 allow for relativemotion to the mounting fasteners 122, 123.

In some aspects, the motor is a brushless direct current motor (BLDC).In some aspects, the motor is an outrunner BLDC motor. In such a motor,the motor spins an outer rotor around its windings. The motor shell hasmagnets on the inside lining and the stator contains a laminate stack ofsteel plates with the motor windings on the teeth. In some aspects, themotor is a disc shaped motor. In some embodiments of the presentinvention, the motor stator has a stator diameter of greater than 2times the laminate stack thickness. In some embodiments of the presentinvention, the motor stator has a stator diameter of greater than 4times the laminate stack thickness. In some embodiments of the presentinvention, the motor stator has a stator diameter of greater than 6times the laminate stack thickness. In some embodiments, the statorstack height is less than 30 mm. In some embodiments, the stator stackheight is less than 20 mm.

In some aspects, as seen in FIG. 8 , there is no directional clutchtypically seen with drive only electric bicycle systems. As there may besome motor drag when coasting the bicycle without such a clutch, inorder to provide a frictionless feel the drive electronics may provide aminimum amount of drive power to the motor while the bicycle iscoasting.

In some embodiments of the present invention, as seen in FIG. 9 , themotor unit is mounted between the rear stay and the chain stay.Similarly to other embodiments described herein, the motor rotationalaxis is forward of the rotational axis of the rear wheel and rearward ofthe forward most portion of the rear rim.

In embodiments of the present invention, the electric bicycle systemwould further include a battery, a motor controller, and the associatedwiring harnesses coupling the motor, the battery, and the motorcontroller together. In some aspects, the battery is a pack composed oflithium ion cells. These cells provide for large energy storage in asmall and light weight package. In some aspects, other types of energystorage such and as a lead acid battery, fuel cell, or other means ofenergy storage could be utilized.

Motor controllers take energy from the battery and convert it into acontrollable form to be utilized to drive an electric motor. Motorcontrollers can have other functions such as processing rider input orcontrolling other functions. Motor controllers may also have the abilityto take energy generated by the motor and convert it to a form to putthe energy into the battery. These types of motor controllers aregenerally referred to as controllers capable of regeneration or regen,but numerous names and types are possible. In some aspects, the electricbicycle system would include a regen capable motor controller.

FIG. 18 illustrates an electric subsystem 400 which may be used inconjunction with electric bicycle systems according to some embodimentsof the present invention. A battery 401 is coupled to a motorcontroller/driver 402, which in turn is coupled to a motor 403. In adrive scenario, the battery provides power 404 to the motorcontroller/driver, which then may modulate the power and provide it 405to the motor 403. In a regenerative braking scenario, the motor mayprovide power 407 through the motor driver/controller 402 and on to 406the battery 401.

In another exemplary embodiment of the present invention, as seen inFIG. 9 , an electric bicycle system is mounted in a location below therear stay of the bicycle frame. In other embodiments, the location ofthe motor could also be above or below the chain stay. Additionalembodiments may or may not have chain stays or seat stays at all, orthere could be asymmetric stays that exist or not exist only on one leftor right side. Numerous examples of structures connecting the rear wheelto the rest of the bicycle frame are possible.

In other embodiments, the rearward portion of the bicycle frame might bemoveable in order to provide suspension. This is sometimes, but notexclusively, referred to as rear suspension.

In some embodiments of the present invention, as seen in FIG. 12 , anelectric bicycle system 300 incorporates a disc brake systemincorporated into the electric drive system. A motor unit 301 is coupledto a bicycle with a mounting bracket 310. A chain 306 drives a drivegear 302 in a similar fashion to the above described embodiments. Thegear mounting bracket 308 supports the drive gear 302 and also supportsa brake disc 303. The fasteners 305 which attach the bracket 308 mayalso attach the disc 303. A disc brake caliper mechanism 304 may be alsosupported by the bracket 310 and is adapted to provide clamping forceonto the disc 303 to provide braking to the wheel. As seen incross-section in FIG. 13 , the thin profiles of the components allow forthe fit of the combined motor and disc brake assembly with similaravoidance of the tire, wheel, the crank, and the user in accord withembodiments described above.

FIG. 14 illustrates an exploded view of the electric bicycle system 300.In some aspects, the motor unit may have a directional clutch 308adapted to allow for the motor to transmit torque in the drivedirection, but to free-spin to allow relative rotational freedom betweenthe motor and the drive gear when the motor is not driving the drivegear. An outer housing 310 is coupled to an internal stator 316, whilethe inner housing 313 is coupled to an exterior rotor 317. A shaft 309couples to the interior of the clutch 309 and is supported by bearings311, 312. An outer shaft is formed in the inner housing 313 and couplesto the exterior of the clutch 309. The outer shaft is supported bybearings 318, 314, to provide support of the inner housing 313 relativeto the outer housing 310. A chain 306 drives the drive gear 302, whichis supported by a bracket 308. The disc utilizes the same mountingfasteners as the bracket 308 and is attached to the disc mountinginterface of the wheel hub.

FIG. 15 illustrates a mounting bracket 170 according to some embodimentsof the present invention. This style of mounting bracket is made tofacilitate the mounting of both a motor and a disc brake caliper to aframe. The mounting bracket 170 includes through holes 171, 172 whichmay be sized to mate to an industry standard disc brake mountinginterface on a frame. Additional holes 173 and 174 are provided toremount a disc brake caliper in an alternate position that may becompliant with a caliper mounting standard. That standard may be for asmaller or larger disc rotor.

FIG. 16 illustrates a mounting bracket 180 according to some embodimentsof the present invention. This style of mounting bracket is a variationof the bracket shown in FIG. 7 , but includes threaded holes 181 and182. Threaded fasteners such as set screws or screws may be mounted inthese holes in order to provide multiple points of contact with theframe that are adjustable.

In some embodiments of the present invention, as seen in FIGS. 17A and17B, an enhanced mounting system is used. A bracket 440 has an interfaceportion 446 adapted to interface with a motor unit. A first mounting 441has a through hole 442 adapted to receive a fastener which may fastenthe bracket 440 to the bicycle frame. A second mounting 443 has athrough hole 441 adapted to receive a fastener which may fasten thebracket 440 to the bicycle frame. A mounting pad portion 445 includes anextended interface area which provides increased lateral stability andload spreading when the bracket is mounted to its mating component. Abicycle frame rear portion 450 may include a bracket mounting area witha first mounting interface 451 with a fastener receiving portion 452. Asecond mounting interface 453 may include a second mounting interface453 with an extended interface area 455 which may pair with the extendedinterface area of the mounting pad portion 445 of the bracket 440. Insome aspects, the interface dimensions other than the extended padportions are standard for a rear disc brake mounting interface.

As evident from the above description, a wide variety of embodiments maybe configured from the description given herein and additionaladvantages and modifications will readily occur to those skilled in theart. The invention in its broader aspects is, therefore, not limited tothe specific details and illustrative examples shown and described.Accordingly, departures from such details may be made without departingfrom the spirit or scope of the applicant's general invention.

What is claimed is:
 1. An electric bicycle system, said electric bicycle system comprising: a bicycle frame, said bicycle frame having a longitudinal axis; a rear wheel coupled to said bicycle frame, said rear wheel comprising: an axis of rotation; a first pedal drive side of said rear wheel coupled to a first side of said bicycle frame; and a second side or said rear wheel coupled to a second side of said bicycle frame; a motor unit coupled to said bicycle frame, said motor unit comprising a low aspect ratio electric motor, said motor having an axis of rotation, wherein said motor unit is coupled to said second side of said bicycle frame such that said axis of rotation of said motor is longitudinally forward of said axis of rotation of said rear wheel and within an outside diameter of said rear wheel; an output gear coupled to said motor; and a drive gear coupled to said second side of said rear wheel, said drive gear mechanically coupled to said output gear of said motor. 